Adjustable gastric banding apparatus have provided an effective and substantially less invasive alternative to gastric bypass surgery and other conventional surgical weight loss procedures. Despite the positive outcomes of invasive weight loss procedures, such as gastric bypass surgery, it has been recognized that sustained weight loss can be achieved through a laparoscopically-placed gastric band, for example, the LAP-BAND® (Allergan, Inc., Irvine, Calif.) gastric band or the LAP-BAND AP® (Allergan, Inc., Irvine, Calif.) gastric band. Generally, gastric bands are placed about the cardia, or upper portion, of a patient's stomach forming a stoma that restricts food's passage into a lower portion of the stomach. When the stoma is of an appropriate size that is restricted by a gastric band, food held in the upper portion of the stomach may provide a feeling of satiety or fullness that discourages overeating. Unlike gastric bypass procedures, gastric band apparatus are reversible and require no permanent modification to the gastrointestinal tract. An example of a gastric banding system is disclosed in Roslin, et al., U.S. Patent Pub. No. 2006/0235448, the entire disclosure of which is incorporated herein by this specific reference.
Over time, a stoma created by a gastric band may need adjustment in order to maintain an appropriate size, which is neither too restrictive nor too passive. Accordingly, prior art gastric band systems provide a subcutaneous fluid access port connected to an expandable or inflatable portion of the gastric band. By adding fluid to or removing fluid from the inflatable portion by means of a hypodermic needle inserted into the access port, the effective size of the gastric band can be adjusted to provide a tighter or looser constriction.
However, the level of tightness of the gastric band may effect the patient's sensations and satisfaction level. In other words, if the gastric band is underfilled, the patient may experience hunger; but if the gastric band is overfilled (and thus “too tight”), the patient may experience tightness in the chest region, suffer from a food bolus blockage, and the like.
Sometimes, adjustment of a gastric band may be desirable in between adjustments made by a physician. For example, during normal operation of the gastric band, the band applies pressure to the outer surface of the upper stomach. However, it may be difficult to achieve the most effective level of tightness, and further, physicians may tend to err on the side of underfilling the gastric band (thereby decreasing efficacy of the gastric band system) as they consider the risk of overfilling the gastric band.
Some attempts have been made to develop a gastric band that promotes an effective fill level. For example, with reference to FIGS. 1A-1B, Lau, et al., U.S. Patent Pub. No. 2010/0191271 discloses an elastic bladder that is in constant fluid communication with the expandable balloon portion of a gastric band in order to continuously adjust the gastric band. With reference to FIG. 1C, Lau, et al., U.S. Patent Pub. No. 2010/0191265 discloses an alternative elastic bladder having four wings.
With reference to FIG. 2A, Coe, et al., U.S. Patent Pub. No. 2009/0216255 discloses a flow control device A that moves fluid between a hydraulic restriction system and a fluid source B. The additional flow control device A controls a rate of fluid flow between the restriction device and the fluid source B. With reference to FIG. 2B, Coe, et al., European Patent Application No. 2 074 970 A1 discloses a separate restriction device and pressure adjustment device C. The pressure adjustment device C regulates a constant force applied by the restriction device using, for example, a bellows and a spring.
With reference to FIG. 2C, Lechner, U.S. Patent Pub. No. 2009/0054914 discloses a controllable stomach band that has a chamber for controlling restriction of the stomach band. The chamber is coupled to a separate pressure chamber D that receives fluid leaving the chamber in the stomach band. The pressure chamber D is separated from the esophageal-gastric junction of the patient's stomach.
Further, with respect to FIG. 3, Steffen, U.S. Patent Pub. No. 2009/0062826 discloses an adjustable gastric band with a “conveyance device” that is powered by a “power storage device.” The power storage device operates the conveyance device to move fluid between expandable chambers to adjust the gastric band.
Accordingly, it is desirable to develop a self-adjusting gastric band that will provide the needed pressure to the stomach to create the stoma and facilitate weight control, but that will also adapt and open up to allow a large bolus to pass through. It is further desirable to create an automatically self-adjusting gastric band that does not require an electrical power source and/or external adjustments, to allow a large bolus to pass through.
Additionally, it is desirable to make the adjustments without additional, complicated fluid control mechanisms, flow rate limiting devices, and/or valves to regulate the transfer of fluid within the self-adjusting gastric band. Moreover, it is desirable to make these adjustments to the gastric band utilizing compliant components to both reduce and restore the constriction of the gastric band.